1. Field of the Invention
The present invention relates to a boot for protecting a constant velocity universal joint disposed, for example, on a driving shaft (power transmission shaft) or the like which transmits power to an axle hub from a differential gear of an automobile, particularly to prevention of damages of a boot by a sharp edge of an end face portion of an outer housing of a constant velocity universal joint.
2. Description of the Related Art
Constant velocity universal joints are used in opposite end portions, for example, in a driving shaft for an automobile. Moreover, a flexible boot is attached in such a manner as to cover a bent portion of the constant velocity universal joint in order to seal grease for lubricating the constant velocity universal joint and to prevent entrance of foreign matters such as dust and water from the outside. Large and small end portions of the boot are usually fastened and fixed to an outer peripheral surface of an outer housing of the constant velocity universal joint on a differential side or a hub side and an outer peripheral surface of a driving shaft portion by fastening means such as bands (see, e.g., page 1 and FIG. 1 of Japanese Patent Application Laid-Open No. 2002-39208).
Moreover, it is known that a surface portion facing the end face of the tip portion of the outer housing of the constant velocity universal joint is formed on the large end portion of the boot on an inner peripheral side in order to prevent the large end portion of the boot for the constant velocity universal joint and the outer housing of the constant velocity universal joint from being shifted in an axial direction.
However, in the above-described boot for the constant velocity universal joint, when the boot for the constant velocity universal joint is bent accompanying a stroke of a suspension or bend of the driving shaft caused by a steering operation, the inner peripheral surface of the boot contacting the end face of the tip portion of the outer housing of the constant velocity universal joint is pressed onto the tip portion of the outer housing of the constant velocity universal joint, and a so-called “bite-in” occurs in some case. When such bite-in occurs, the boot needs to be prevented from being damaged by a sharp edge or burr of the tip portion of the outer housing of the constant velocity universal joint by machining.